High

CVE-2026-5039 — Predictable Default Cryptographic Key Used for DES Encryption in TP-Link TL-WL841N

TP-Link TL-WR841N v13 uses DES-CBC encryption in the TDDPv2 debug protocol with a cryptographic key derived from default web management credentials, making the key predictable if device is left in default configuration. A network-adjacent attacker can exploit this weakness to gain unauthorized access to the protocol, read debug data, modify certain device configuration values, and trigger device reboot, resulting in loss of integrity and a denial-of-service condition.

Published Apr 23, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: TPLink

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.2% (30-day exploitation probability)+1
Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.21%

ahead of 10% of scored CVEs · Oct 15, 2026

Affects

TP-Link Systems Inc.

TL-WL841N v13 and 1 more

CVSS base

8.8

High · 3 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (TP-Link Systems Inc. TL-WL841N v13, TP-Link Systems Inc. Tl-wr841n Firmware).
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
TP-Link Systems Inc.	TL-WL841N v13	< 0.9.1 Build 20231120 Rel.62366	Vulnerable	CVE Program (cve.org) e CISA ADP
TP-Link Systems Inc.	Tl-wr841n Firmware	< 231120	Vulnerable	NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Adjacent

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
6.1	CVSS 4.0	Medium	—	—	f23511db-6c3e-4e32-a477-6aa17d310630 via NIST National Vulnerability Database
6.1	CVSS 4.0	Medium	—	—	TPLink via CVE Program (cve.org) e CISA ADP
8.8	CVSS 3.1	High	2.8	5.9	nvd@nist.gov via NIST National Vulnerability Database

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-1394

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 15, 2026 · 3 reading(s) · max 0.21%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Not enough vector or weakness data: use the affected application’s logs as a starting point.

application logs

Timeline

What happened to this CVE, newest first.

2026
Affected products added · tp-link systems inc./tl-wl841n v13
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
CVSS changed · 8.8
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
Apr 23, 2026 · TPLink

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

1 on the record

www.tp-link.com/us/support/download/tl-wr841n/v13/
Product, patch, NIST National Vulnerability Database

Elsewhere on this site

TP-Link Systems Inc.
every CVE for this vendor

CWE-1394
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2026-9105 Authenticated Stack-Based Buffer Overflow in TP-Link TL-WR841N Web Interface Jun 29, 2026
High CVE-2026-3622 Denial-of-Service Vulnerability in UPnP Component of TP Link's TL-WR841N Mar 26, 2026
Medium CVE-2026-3227 Authenticated Command Injection on TP-Link TL-WR802N, TL-WR841N and TL-WR840N Mar 16, 2026
High CVE-2025-9014 Null Pointer Dereference Vulnerability on TL-WR841N Jan 15, 2026
High CVE-2025-9377 TP-Link Archer C7(EU) and TL-WR841N/ND(MS) OS Command Injection Vulnerability KEV Aug 29, 2025
Medium CVE-2023-50224 TP-Link TL-WR841N Authentication Bypass by Spoofing Vulnerability KEV May 3, 2024

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-5039 is "Predictable Default Cryptographic Key Used for DES Encryption in TP-Link TL-WL841N", rated High. It affects TL-WL841N v13 (TP-Link Systems Inc.); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 8.8 describes technical severity. EPSS 0.21% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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